Speedometer.



G. H. DRAPBR. ammonium. APPLICATION FILED JUNE 12, 1908.

Patented 1m29, 1908.

2 SHEETS-SHEET 1.

l @Zava/aes;

'0.11. DRAPBR.

SPBEDOHBTBB. armenio! rmzn mm 12. nos.

908,079. Patent@ Dec. 29, 1908.

2 SHEETS-SHEET 2.

, STATES CLARE HfDRAPER, OF HOPEDALE, MASSACHUSETTS.

No. 908,079. 'i

Hopedale, county of Worcester, State of Massachusetts, have invented an Im rove-` ment in Speedometers, of which the ollowing description, in connectionwith the accompanying drawing, is a specification, like letters on the drawing representing like parts.

This invention has for its object the production of a novel apparatus for measuring and indicating the speed at which a moving object is-traveling, such, for instance, -as an automobile, though mynovel speedometer is not by any means restricted to such use;

Speed is measured by the distance traveled in a given eriod of time,'and`in all speedometers Wit which I` am familiar the operation depends upon the distance and some factor other than time, such as centrifugal force, the head of a liquid, etc., while it has been my object to devise a speedometer dependingon the two factors of distance and time.

' Time is ordinarilyl measured by a clock mechanism or time movement of' any suit` able character, and distance by the revolutions of a wheel. of given circumference. In my present invention I combine these with optical illusion to-indicate speed in a manner w lich must be accurate so long as the clock mechanism, escapement, or time movement (whichever term be used) is regulated properly, and the wheel is'of proper circumference and acts without slipping;

So far as the optical illusion is concerned it is based on thel following well known facts, to witz-When a succession of similar and moving images are presented. to the eye in the same posit-ion, if the intervalsof time between such presentations are short enough the several images appear to the eye as a single stationary image. Also, if the images are presented in successively'varying positions the resulting image appears to be in motion from the position iirstseen to that last seen, the zoetrope and kinetoscope being forxi'ns of apparatus operating on this prin# c1 e; l Iflonceive a cylinder with -agiven number of spots, say ten, arranged around its circum-Y ference at equal ydistances apart in a plane at Patented nee.l 2e, 190s.

l right angles -to its axis, and a concentric sleeve revoluble about the axis of the cylinder and having ten openings corresponding `in position to the ten spots. Looking at a spot through one of the openings let'the cylinder and sleeve revolve at the same speed but in opposite directions. When the second opening takes the place of the first one the second spot will occupy the position, of the first spot, and the appearance to the eye is unchanve y v If' the interval of time elapsing between the changes in the positions of the spots and openings is short enough the eye has apparently observed but one stationary spot, no movement of the spots being a parent. NOW suppose the sleeve to have ut one opening, and to revolve ten times as fast as the cylinder, then every time the opening opposite the eye a little later or a little earlier 1n comparison, and consequent-ly would appear to be moving in the direction of `rotation ofthe shutter, or in the direction of rotation of the cylinder, according to the movement of the former faster or slower than ten times as fast as the cylinder.

From the foregoing it will be manifest that astationary appearance of the spots indicates a relative speed or ratio of 1 to 1, or 10 to 1, depending upon whether the shutter has ten openings or one opening.

The number ofspotsdivided by the number of shutter openings gives the ratio of speed as shown by apparently stationary spots. y

In my invention I make use of the optical illusion that almoving series of separate and` constant speed, say one revolution per second, by any suitable clock mechanism or timemovement, and the coperating member 'or shutter is so geared 'as to be revolved (by the wheel'of an automobile) once per second .if the caris traveling at the rate. of one mile an hour. Consequently a moving row of spots revealed by an equal number of moving s utter openings will appear to the eye at a given place as one stationary spot, when the speed of the car is one mile er hour. If the car travels atten. miles an our theshutter `Will be revolved ten times per second, and a l roW of s ots revealed by a roW of one tenth the number of openings will a pear to the eye as one stationary spot. Sim' arly, any numof miles per hour, (Within the limits of the speedometer) may be indicated by a proper ratio of shutter o enings to the spots which are arranged on the cylinder behind them. I Vhave discovered by experiment that when one row of spots app-ears stationary the rows indicating the next 'gher and the next lower speeds seem to move slowly in opposite directions, thus making it comparatively easy for the eye to pick out the row which ap pears lto be stationary and which indicates the rate of speed. Rows of spots for indicating s eeds quite different trom the one indicate ordinarily ap ear blurred and indistinct, although multip es of the speed indicated sometimes apear stationary, but factors do not. Thereore, in my speedometer the first a parently stationary spot observed, nearest t 1e row in?l dieating the lowest speed, is the one which is indicating the speed of the car at that moment.

If a given spot is observed through a given lopening in the shutter-member in a given position, all in the line indicating a certain speed, av different definite spot Will be seen through ythe' next opening 'of the shutter member in exactly the same position as the first spot Was seen, thereby giving to the eye the impression that but one spot has been seen in one osition, Whereas in reality two spots have. een observed, the observation and its impression' being manifestly an optical illusion.

Figure 1 is a front elevation of a speedometer embodying one practical form of my invention, the outer,. stationary casing being partly broken out to show a portion of the revoluble shutter, Which latter'is also broken out to show the inclosed revoluble image member or cylinder; Fig. 2 is a vertical diametral section of the apparatus shown in Fig.'1, and centrally broken out to save space Fig..3 is adevelopment ofthe shutter; Fig. 4 is a similar development ofthe surface of the image member.

In the embodiment of my invention herein shown I provide an upright cylindrical case 14 .having an attached bottom 2, Fig. 2, with a 65 central tubular boss 3, a top 4 having a ceni eoao'ze tral tubular bossV5 being suitably secured in the uplper end of the casing, brackets 6 being suitab y mounted on the top and bottom of the casing to enable the latter to be attached in fixed position on the automobile in sight "o of the operator. A

A bevel gear 7 is provided with an elongated sleeve-hub 8 rotatably mounted in the boss 3, the hub extending upward to a oint near the boss 5, and theshaft 9 of a evel gear 10 is rotatably mounted in said 'boss 5, the shaft 9 in ractice extending through the length ofthe sleeve-hub 8 and being freely rotatable therein. The bosses 3 and 5 thus serve as bearings for therevoluble portions of the apparatus, the sleeve-hub 8 and the shaft 9 being shouldered, as shown in Fi 2, to bear respectively against the outer en s of the bosses 3 and 5.

A cylindrical shutter 11 having attached ends 12, 13, is mounted within the case coaxially therewith, a hub 14 on the end 12 loosely embracing the sleeve-hub 8 while a hub 15 on the end 13 is iixedly secured to the shaft 9 by a set-screw 16, Fig. 2, the hubs abutting against the inner ends of the bosses 3 and 5, as shown.

Within the shutter and concentric therewitha c Tlindrical image member 17 is mounted, liubs on its upper and lower ends 95 18, 19 being ixedly secured to the sleeve-hub f 8 by suitable set-screws 20, the hubs of the image member 17 abutting against the inner ends ofthe hubs 14 and 15 of the shutter, and by an inspection of Fig. 2 it will be seen that the arrangement of the parts is such that no endwise movement is permitted with relation to the case 1. Rotation of the shaft 9 effects rotation of the shutter 11 While rotation of the limage meinber or cylinder 17 is effected by rotation f the gear 7 and its sleeve-hub S.

By means of a bevel gear 21, Fig. 1, suit`- ably connected with any suitable form of clock mechanism or time movement, indicated in Fig. 1, at CX the image member is 110 revolved at a constant predetermined speed, and by a bevel gear 22 meshing with the gear 10 and connected in any suitable manner with one of the Wheels 'of the automobile the shutter 11 is driven at a variable speed ac- 115 cording to the speed attained by the vehicle.

In practice l drive the image member 17 at the rate of one revolution er second and the shutter member 11 at tie same speed when the vehicle s eed is one mile per hour, 120 so that the R. P. (revolutions per minute) will be in the same ratio to the number of' minutes as the R. P. M. of the shutter is to the number of miles per hour, the shutter bein so geared to the vehicle Wheel that the 125 num er of revolutions per minute of thc` shutter correspond relatively to the miles per hour. That is, at one mile per hour the image member will make sixty revolutions in one minute, and the shutter will be rotated 130 imagemember, giving the. equation to oneI mile per hour. For a speed ,of ten miles-per hour we have 1 1.:;600':10, the shutter. being rotated at ten times the former speed, and so on for other speeds. l As vshown in Fig. 1 the case 1 isprovided with a longitudinal slot or sight opening 23 en thel sidenearest the' observer, and adjacent this-'sight opening at omi/side thereof I lace a vertical row'of index mlmbers, this Instance running from 1.to 235, in regular order. These index numbers in cate, in a manner to be explained, therate of-'speed at which vehicle is running.

The' cylindrical surface of the image member 17 is provided with twenty-nwe circular series of images, herein. sho-m as rectangular s ots, and: prera-bly of like dimensions tiiroughout, the vertical spacingiof the series corresponding to the of they index numbers on`the case.

An inspection of tl1e-developed surface of the image member, Fig. 4, will make clear the relative larrangement'.and number of. spots orL images inthe tvireinzy-flve; series, it being understood that this arrangement 1s based .upon the previously explained speed ratios, etc., of the moving parts of the apparatus.

Any spot or image is indicated' at 24v.

The shutter is provided with openingsarranged in circular series, and each o enjng is of a "vertical dimension substantia vy correspending tothe heioht of an image, all of the s utter`^openings thus being of the same height, but 4they vary in Width, as will. be apparentA from an -inspection of Fig. 3. 'New with a single shutter opening the number ol images in a given series on the imagemember 17 would be e ual to the number of miles indicated but Wit more' than one shutter opening for a given series of images the num-` ber of miles indicated would be equal to the number of images in the proper series divided by the number of shutter o enings correspending. For exam le, in t e present a paratus, at a speed o 25 miles per lhour t e shutter 11 Will revolve 25 times as fast as the image member 17, and I have-shownl50 lmagesor spots in the lowermost series on said member 17 while the shutter 11 has but two openings 25, Fig. 3, corresponding to` that series of images. Hence the number of images 50, divided by 2, gives 25, the number of miles per hour.

Taking the u 32 are shown in fig; 4, andthe-same num er giving 1,- the number` of miles lhat is, at one mile er hour t ima e the index number 15 is ermost series of ima es,

.wlth a vehlclc wheel of a given. dlameter 1t of shutter?.openings. isK shown at 26, Fig. 3, the former when 4divided by the llatter r our.

member 17 the shutter 1 1'are revolved oppositely butv at the same speed, and as a. result the observer looking at the sight vopening '23- of the casing will see at the top vvhat appears to be av single, stationary image opposite thei index number 1, while the other images will appear to moveand Will'be blurred or indistinct. If the speed increasesto 25 miles per hour, the apparentlystationary rimage will appear to the observer oppositeQ the index number 25 bn the case, viewing Fig. 1,'while all the other images- Will appear to-I *bel in .motiom In like manner, for any intermediate speed the stationary?y imagewill appear opposite the inrlex'v number corresponding to that speed, while the other images will -bein motion and blurred.

` At a speed intermediate any` indexed speed the images corresponding to the next .speeds above and below will appear to the observer toA move slowly in .opposite directions. Eor example, if the observer notes that the series of images corresponding to movi onedirectionand the series of images corT 'responding to the index `number 16 is moving slowly in the opposite direction he knows that the speed is between 15 and 16 miles per hour.

The second and lthird rows of shutter openings V27 are the same 1n number, sixteen, While the second series of images numbers thirty-two, and the third series forty-ei ht, giving speeds respectively of two an threeA miles per hour.

Rows four to el ht, inclusive, of shutter openings, indicate on Fig. 3- by the reference number '28, are each made up of eight openings, andthe number of images in any .correspondin series is equal to the number ofy miles or that series multiplied by 8. Then come seven rowsof openings '29, Fig. 3, With four shutter openings m each row, the number of images 1n a given corresponding series bein equal to the number'o miles indicated by that series multiplied by 4. f I s From the foregoing description of the apparatus its mode of operation will be c ear, and `its theory of operation evident. The 4images may be of any desired shape and as herein shown they 'are rectangular spots.l

AIn actual practice I ndit is desirable to 'make the outer surface of the shutter black,

and also to make `the images red orWhite slowly' non- .a black background on the image Vmember` A Having designed the apparatus forv use J is applicable to vehicles having Wheels of different, diameters by a. simple change in the -intermediate gearing so as to operate as hereinbefore set forth.

My invention is not restricted to the those skilled in the art Without departing from the spirit and scope of my invention as set forth in the annexed claims.

Having fully described my invention, what I claim as new and desire to secure by Letters Patent is l. In a device for measuring speed, a member moved at constant speed, means to move it, a second member, means to move it by the object Whose speed is to be measured and at a variable speed determined by the speed of such object, said members being rovided with means to present to the eye o the observer, when said members are in motion, an apparently stationary image in any one of a series of diierent positions according to the relative speeds of rotation of said members.

2. In a device for measuring speed, a member rotated at constant speed and having Va plurality of images thereon, means to rotate said member, a second member, means to rotate it by the object Whose speed is to be measured and at a speed determined by the speed of such object, said second member being concentric With the image member and having series of openings therein through which the series of images may be seen, the images and openings of corresponding series being so related that at one speed of the object an image of a (particular series will appear to be at rest, an at another speed an image of a different series Will appear to be at rest.

3. .In a device for measuring speed, a rotatable shutter having series of openin s,

means to rotate the shutter by the object t e speed of which is to be measured, an ima e member behind the shutter and opposite y rotated at a constant speed, and means to rotate the image member, said member having series of images thereon temporarily visible ,through the openings in the shutter, the. images being in the same ,ratio to the cor-..

responding shutter openings as the ratio of the speeds to be indicated" is to unity,

whereby at such lratio o-.speeds theimages ofna series indicative of a certain speedwill appear stationary throughthe shutter openings. Y

4. In a device for measuring speed, a'shaft rotated at constant speed, means to rotate it, a shaft adapted to be rotated at a rate in aecordance with the speed of the object the speed of which is to be measured, and means operated by said shafts and dependent upon optical illusion for the impression reduced upon the eye of the observer to in icate the ratio between the speeds of the two shafts.

5. In a device for measuring speed, a member rotated at a constant speed, means to rotate said member, a second member, means to rotate it by the object Whose speed is to be measured and at a speed determined by lthe speed of such object, said members being concentric, one ofthe members having a plurality of images thereon and the other member having series of openings therein throu h which the series of images may be seen, t ie images and openings of corresponding series ject an image of a particulary series will appear to be at rest, and at another speed an image of a different series will appear to be at rest.

6. A device for measuring speed, including an image member, amember having openings through which the images can at times be seen, means to move one of said members at constant speed and, means to move the other member according to the speed of the obiect Whose speed is to be measured, to indicate the relative, speed of said members by the substantially stationary appearance of the images as seen through the member having openings therein.

7. In a speedometer, a rotatable member having a plurality of series of images thereon, a shutter member in front of it and having series of openings through which the images can at times be seen, means to rotate one of said members at a constant s need, and means to rotate oppositely the otlier member by theobject Whose speed is to be measured, to indicate the relative speeds of said members by the substantially stationary ap earance of the images of a series seen throug the cooperating openings in the shutter member.

8. In a speedometer, an image member means to rotate it at a constant speed, a concentric, o positely rotatable shutter driven at a rate etermined by the speed of the ob-v .the rformer divided by the atter equals the corres ending` number of speed units per unit o time; `and an vinclosing case having 'a sight opening, an apparently stationary,

. vimage visible in. such opening indicating by its position With relation to the ends of the opening the speed of the object.

9. In a speedometer, an image member means to rotate it at a constant speed, a concentric, oppositely rotatable shutter means by which the shutter is rotated by the object whose speed is to be'measured at such a rate that the ratio of shutter .revolutions per .minute to the number of miles per hour eqals the revolutions per minute of the image member to the number of minutes,

`whereby at any speed of the object the images of one fof the series will ap ear stationary through the corresponding s utter openings, a stationary inclosing casel for said shutter and image member, having a sight opening, and a series of index numbers at one side of the opening, the number opposite the apparently stationary image denoting the speed in miles per hour. l

10'. In aspeedometer, an image member means to rotate it at a constant speed, a con-v centric, op ositely rotatable shutter, means by which t e shutter is rotated by the object whose speed is to be measured at such a rate that the ratio of shutter revolutions per "minute to the number offmiles per hour equals the revolutions per minute of the, image member to lthe numberl of minutes, whereby at any speed of `theobject the images of one ofthe serieswill appear stationary through the corresponding shutter olpenings, anda stationary inclos' case Vfor t e shutter-and image member, aving a sight o ening crossing all the' seriesof images, throng which openin the indications of the o speedometer are |visib e to theobserver.

name to this speciication, in the es per hourat which l the vehicle is traveling, the revolutions er minute of the image member to the num er 45 of minutes having the same ratio as the revolutions of the shutter per minute to the miles per hour, said shutter having a plurality of series of openings corresponding to the series'x of ima es, .whereby at a given speed the images o the corresponding series will appear `substantially statlonary, and a non-rotating' case 'nclosing the shutter and image member and having an elongated, relatively narrow sight opening through which the images may be observed.

12. In a s eed-measuring device for vehicles, a cylin rical image member rotated at a constant speed and having a plurality of circular series of males arranged thereon corresponding to derent speeds per hour, means to rotate said member a shutter concentric with and inclosing said image member, means `by which the shutter is rotated' oppositely thereto by vone of the vehicle 6,5 Wheels at a'rate governed by the speed of the vehicle, the revolutions'per minute of -the image member to the number of minutes having the same ratio as the revolutions of the shutter per minute to the miles per hour,

said 'shutter having a plurality of 4series of openings corresponding to the series of images, whereby at a given speed the corresponding'series of images will appear substantially stationary, and a non-rotating Ycaseinclosing the image member and shutter and 'having a lo "tudinal'" sight ening'" through which thenilllages may be obslerved.

In testimony whereof, I have signed my presence of. two subscribing witnesses. l

CLARE' H, DRAPER.

` Witnesses: l

EDWARD F. ALLEN,

FREDERICK S. GREENLEAF. 

